Hydraulic fuel system



July l1, J. M. RTH ET A1." 2,353,269

BYDRAULIIG VFUEL SYSTEM Filed Sept. 21:. 1940 3 Sheets-Sheet 1 ENG/NE (l3 i r 212.523. 'Il

July 11, 1944- M. ROTH `rsrm. 12,353,269

HYDRAULIC FUEL SYSTEM Filed sept.'21. 1940 Julyll, 1944- Y J. M. ROTHErm. y 2,353,269

` HYDRAULICY FUEL SYSTEM Filed sept. 21 1940 s sheets-sheet :s

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JEM (l Patented July 1l, 1944- i HYDRAULIC FUEL SYSTEM Jay M. Both,Euclid, and Louis G. Burns, East Cleveland, Ohio, assignors to PescoProducts Co., a corporation of Ohio Application september 21, 1949,serial No. 357,826

2 Claims.

This invention relates to fuel supply systems and particularly toaircraft fuel feeding systems for high altitude flying.

It has been found that certain limitations in fuel systems heretoforeavailable have resulted in the occurrence o f a condition known to theart as vapor lock. It has also been determined that this vapor lockcondition is due largely to the occurrence of reduced pressure in thefuel feeding system, which pressure becomes sufliciently low to causethe fuel to be pulled apart and air bubbles incorporated therein. Anumber of factors have been credited with producing these low pressureconditions, including: flying at extremely high altitudes; locating thehighly volatile fuel tanks at an elevation on the aircraft below that ofthe means for introducing fuel into the engine; locating theseinstrumentalities remote with reference to each other: and maneuveringthe craft as for example, banking, diving and the like.

Previously available systems have failed to fully take into account allof the factors having an influence upon the proper feeding of a.volatile fuel from the supply tank to the means for introducing the fuelinto the engine and more particularly have these previous systems failedto provide the necessary arrangement of means for counteracting theeiects referred to above.

It is an object of the present invention to provide an improved volatilefuel pumping system for transferring fuel from the supply tank to theaircraft engine under circumstances wherein the tank must necessarily belocated remote from the engine and in some instances at anI elevationconsiderably therebelow, our improved system being particularlycharacterized by the provision of means for preventing the-occurrence ofpressure A in the fuel system of a low value such that the fuel will bepulled apart and air bubbles incorporated therein.

It is a more particular object to provide such an arrangement of meanswhichI is capable of compensating for or overcoming the several pressurereducing effects peculiar to aircraft and including flying at extremelyhigh altitudes; nor- (Cl. ISB-36.4)

no appreciable by-passing of volatile fuel from the outlet of the fuelpump back to the inlet thereof such for example asis common in currentsystems, and which results in whipping up the volatile fuel and theincorporation of air bubbles therein.

Another specific object of this invention is the novel adaptation to thesolution of the above problem of the variable eccentricity type ofadjustable displacement fuel pump disclosed in Johnson Patent 2,192,266.

T'he above and other objects, advantages and uses of our invention willbecome more apparent from a reading of the following specification takenin connection with the appended drawings which forma part of thisspecification and wherein:

Fig. 1 Ils a broken-away schematic view in perspective illustrating apreferred arrangement of our fuel system on an airplane;

Fig. 2 is a schematic view in elevation indieating the relativedisposition of the elements cated generally byline 3 3 of Fig. 2;

lso

mal differences in the elevation of the engine and the fuel tanks; andmaneuvering such as banking, turning, diving, and the like.

A more detailed object is to provide a volatile fuel pumping system forproducing the above results wherein only that amount of fuel is movedfrom the tank along the fuel line to the fuel introducing means that isrequired by the aircraft engine at any particular time there being VFig. 4 is-a transverse cross-section taken substantially on the lines 44 of Fig. 3;

Fig. 5 is a transverse cross-section view taken substantially on line5-5 of Fig. 2 showing a. variable displacement fuel pump particularlyadapted for use in our fuel system;

Fig. 6 is an axial cross-section view indicated generally by the lines 66 of Fig. 2 illustrating the interior construction of a preferred formof hydraulic motor for driving the variable displacement fuel pump;

Fig. 'I is a broken away section view taken 'substantially on the lines1-1 of Fig. 6;

Fig. 8 is a developed view showing the form of the housing structureembracing the motor rotor and the path of flow of driving fluid throughthe motor.

Referring to Fig. l, there is illustrated schematically in perspectiveanv aircraft indicated generally at l0 embodying a preferredmodification of the fuel feeding system forming the subject matter ofthe present invention. Airplane i0 includes the usual outwardlyextending wing structures il and the forwardly protruding propellerdriving motors I2 of one conventional form to which this invention isapplicable. 'I'he englnes or motors i2 are provided with the usual formof carbureter or other fuel introducing means indicated generally at I3,fuel being supplied thereto from a selected one of a plurality ofvolatile fuel supply tanks |4 carried in the wing structure I I, thisfuel delivery being accomplished by means of our novel fuel pumpingarrangement indicated generally at I5, the pumping arrangement for oneengine only being illustrated in order t simplify the disclosure.

Referring particularly to Fig. 2, it will be seen that our volatile fueltransfer or pumping system |5 comprises essentially a variabledisplacement fuel pump I6 located relatively close to or below the fuelin the tanks I4 and arranged to push or force the volatile fuel upthrough line Il to the carbureter I3 as differentiated from pulling orsucking up the same 'to increase the elevation thereof. It is importantto note that pump I6 is provided with means for varying the displacementthereof in accordance with changes in the pressure that occurs withinthe fuel introducing means or carbureter I3. By providing an eiiicientand variable displacement fuel pump such as that indicated at I6 to behereinafter described A in greater detail and by arranging to vary thisdisplacement in accordance with the most accurate index of -fuel demand,namely the pressure condition within carbureter I3 we have made itpossible to thus overcome or compensate for all of the many variablespresent under aircraft ilying conditions that normally cause fatalreductions in the fuel pressures accompanied by vapor loc Essential tothe successful operation of the present system is the hydraulic uiddrive, comprising the constant displacement hydraulic generator or pump2| driven directly from the aircraft engine I2 and coupled by means ofclosed line or circuit 22 with constant displacement hydraulic motor 23attached to the variable displacement fuel pump |6 for driving the same.Also included in closed line or circuit 22 is an Voil tank oraccumulator 24. While it is contemplated that oil will normally be usedin lcircuit 22, other fluid power transmitting mediums such as glycerinemay be employed to equal advanta e. ceig'ned it is merely important thata liquid medium be employed which has a much lower volatility than thatof the liquid fuel beingsupplied to the aircraft engine, since lit isnecessary to maintain at a minimum the amount of whipping and consequentvapor inclusion, this being particularly significant at high altitudes.

With reference to the details of the variable displacement fuel pump, wehave found that a pump constructed in general conformity with thedisclosure of Johnson Patent 2,192,660 functions in a particularly noveland advantageous manner when employed as disclosed in Figs. 1, 2 and 5.Referring to Fig. 5 it will be seen that the displacement of pump I6 isvaried by vertically adjusting sleeve 30 relative to the fixed axisrotor 3|, this adjustment being accomplished by exposing the upper sideof diaphragm assembly 32 to the pressure conditions existing in thecarbureter |3, the connection being made through line I8, and byexposing the under side of diaphragm assembly 32 to the dischargepressure -of pump I6 through passage 33. In further detail multiple.

pumping vanes or blades 34 reciprocate with reference to the fixed axisrotor 3| as the same revolves causing fuel to be drawn into anddischarged from the pump, these vanes having their inner edges inrunning engagement with a floating tubular member 35 limiting the inwardmovement So far as the present invention is con- 'of severalcommercially available forms.

thereof. Adjustable threaded stop 3B determines the maximum eccentricrelation between the rotor 3| and sleeve 30 and hence the maximumdisplacement of the pump. Elongated coil spring 31 engages the closedend of tubular connector 38 and urges the sleeve 30 in the direction ofgreatest eccentricity with a pressure which is determined by anadjustment assembly indicated generally at 39. It will therefore be madeto appear that three things influence directly the relative eccentricityof the sleeve and rotor and consequently the displacement of the pump,namely; the pressure within the fuel introducing means or carbureter I3acting through line I3 on top of diaphragm assembly A32; the dischargefuel pressure acting on the under side of diaphragm assembly 32 throughpassage 33; and the pressure of spring 31 acting in the same directionas the pressure on top of the diaphragm.

The particularly successful results obtained from the use in combinationof this pump constructed in the manner disclosed is especiallyattributed to two things: first, the relatively large area vdisc-likediaphragm assembly being both sensitive to minute changes in thepressures to which it is subjected and being sufficiently strong toquickly adjust the relative eccentricity between the sleeve and rotornotwithstanding the remote location of this pump assembly with referenceto the carbureter and; secondly, the positive and effective pumpingaction of this vane construction through a wide range of displacementswithout any appreciable accompanying re-circulation or whipping of thefuel sufncient to cause the inclusion therein of vapor or air bubbles.

While other commercially available forms 'of constant displacementhydraulic generators or pumps may be employed at 2| we prefer the vanetype constant displacement generator of the general type disclosed inJohnsons Patent 2,026,739 and comprising essentially a similararrangement to that of Fig. 5 except that the sleeve 40 is notadjustable to vary the eccentricity thereof with reference to fixed axisrotor 4|. The constructions are otherwise essentially the same,including inlet 42, outlet 43 and reciprocable vanes 44.

Likewise, hydraulic motor 23 may take any one However, we have found theconstruction shown in Figs. 6, 'I and 8 to be particularly adaptable foruse in this connection, the same being of the type covered by JohnsonPatent 2,202,911. This hydraulic motor comprises essentially a rotor 53having axially reciprocating vanes or blades 5I adapted to be actuatedby a pair of cams 52 and 53 located adjacent opposite edges thereof forcausing these vanes to respond to the uid pressure stream delivered byhydraulic generator 2| through closed circuit 22, the fluid followingthe path through the motor indicated generally by the arrows 54,entering inlet port 55 and passing out of outlet port 56. Intermediatehousing sleeve 51- embraces rotor 50 and is formed with complementaryports and connecting channels for directing the flow as indicated by thearrows 54.

It will be observed from the above that by employing a constantdisplacement hydraulic generator 2| and a constant displacementhydraulic motor 23, we have made it possible to avoid the use ofcomplicated control units for the oil or other fluid medium in closedcircuit 22, it being necessary to use only a simple accumulator tank 24having an inlet and an outlet with no complicated control mechanism inthe tank.

A conventional supercharger assembly indiaasaaee ,cated generally at 60is employed for the purpose of raising the pressure of the airintroduced into the carburetor I3 with which it communicates throughline 6l.

In addition to the above, therewill of course be employed the necessaryconventional equipment forming no particular part of the presentinvention, and a detailed description thereof is deemed unnecessary.This may include among other things a strainer 65 receiving fuel fromselected ones of tanks I4 through distributor valve 66 and deliveringthe same to the inlet side of variable displacement pump I6.

While we have described our invention in connection with certainspecific embodiments thereof, it is to be understood that this is by wayof illustration and not by way of limitation, and that the scope of ourinvention is to be defined solely by the appended claims.

We claim:

1. In ay high altitude volatile fuel supply system for aircraft motors,including carburetor means adapted to be mounted adjacent an aircraftmotor forintroducing fuel therein, means providing a supplyof volatilefuel located at an elevation normally below that of said introducingmeans, the combination therewith of means for moving said volatile fuelfrom said lower elevation to said carburetor means located thereabovewhile maintaining the pressure of said fuel being moved at a value abovethat point below which vapor lock would normally occur, said meanscomprising' a rotary fuel pump located at a level not substantiallydifferent than that of said supply and in communication with saidsupply, said means being effective to push said fuel from said lowerlevel up to said introducing means, a liquid pressure responsiveconstant displacement rotary motor for driving said fuel pump, aconstant displacement rotory liquid pressure generator adapted to bedriven directly i from said aircraft motor, means defining a closedliquid circuit connecting said pressure generator and said liquidpressure responsive motor, said circuit including a relativelynon-volatile liquid, said fuel pump having a fixed axis rotor supportinga plurality of reciprocable blades embraced by an eccentricallyadjustable sleeve for varying the displacement of said fuel pump, andmeans for adjusting said sleeve relative to said motor comprising adiaphragm assembly connected thereto, means for exposing a first side ofsaid diaphragm assembly to the discharge pressure' of said pump andmeans for exposing the opposite side of said diaphragm assembly to thepressure within said introducing means whereby to deliver fuel to saidintroducing means at a substantially constant pressure.

2. In a high altitude volatile fuel supply system for aircraft engines,including a carburetor adapted to be located adjacent an aircraft enginefor introducing fuel therein, a volatile fuel supply tank arranged to belocated remote from and below the elevation of said carburetor, a fuelpump arranged to be carried byl said aircraft and located at a level notsubstantially different from that of the fuel in said tank for receivingfuel from said tank and forcing the same under a predetermined minimumpressure to said carburetor,'a fuel delivery line leading fromsaid pumpto said carburetor, a constant displacement liquid pressure responsivemotor for driving said fuel pump indirectly from said aircraft engine, aconstant displacement liquid pressure generator driven directly fromsaid aircraft engine, means dening a closed liquid circuit includingsaid generator and said motor for circulating therethrough asubstantially constant volume of non-volatile liquid at a rate dependingupon the speed of rotation of said generator, all of said liquid beingcirculated through said liquid pressure responsive motor, said fuel pumpbeing provided with means for varying the displacement thereof, andmeans responsive jointly to the discharge pressure of said pump and tothe pressure in said fuel introducing means effective to operate saiddisplacement varying means whereby to produce a constant fuel deliverypres- Vsure at said fuel introducing means notwithstanding the effectsattendant to flight, including change of altitude and maneuvering.

JAY M. ROTH. LOUIS G. BURNS.

